Al-Si-Mg-Mn casting alloy and method

Abstract

An improved Al-Si-Mg-Mn casting alloy that consists essentially of: about 6.0-9.0 wt. % silicon, about 0.2-0.8 wt. % magnesium, about 0.1-1.2 wt. % manganese, less than about 0.15 wt. % iron, less than about 0.3 wt. % titanium and less than about 0.04 wt. % strontium, the balance aluminum. Preferrably, this casting alloy is substantially copper-free, chromium-free and beryllium-free.

What is claimed is:  
     
       1. An aluminum casting alloy composition that consists essentially of: about 6.0-9.0 wt. % silicon, about 0.2-0.8 wt. % magnesium, about 0.1-1.2 wt. % manganese, less than about 0.15 wt. % iron, less than about 0.3 wt. % titanium and less than about 0.04 wt. % strontium, the balance aluminum with incidental elements and impurities, the alloy being substantially copper-free, chromium-free and beryllium-free. 
     
     
       2. The casting alloy of  claim 1  which contains about 6.5-8.0 wt. % silicon. 
     
     
       3. The casting alloy of  claim 1  which contains about 0.45-0.7 wt % magnesium. 
     
     
       4. The casting alloy of  claim 1  which contains about 0.1-0.5 wt. % manganese. 
     
     
       5. The casting alloy of  claim 1  which contains less than about 0.2 wt. % titanium. 
     
     
       6. The casting alloy of  claim 1  which contains about 6.5-8.0 wt. % silicon, about 0.45-0.7 wt. % magnesium, about 0.1-0.5 wt. % manganese, less than about 0.15 wt. % iron and less than about 0.2 wt. % titanium. 
     
     
       7. The casting alloy of  claim 1  which is high pressure die cast to make aerospace structural parts therefrom. 
     
     
       8. The casting alloy of  claim 1  which is squeeze cast to make aerospace structural parts therefrom. 
     
     
       9. The casting alloy of  claim 1  which is semi solid formed into an aerospace structural part. 
     
     
       10. The casting alloy of  claim 1  which has an ultimate tensile strength greater than about 45 ksi. 
     
     
       11. The casting alloy of  claim 10  which has an ultimate tensile strength greater than about 50 ksi. 
     
     
       12. The casting alloy of  claim 1  which is substantially blister-free. 
     
     
       13. An aerospace structural component cast from an alloy composition that consists essentially of: about 6.0-9.0 wt. % silicon, about 0.2-0.8 wt. % magnesium, about 0.1-1.2 wt. % manganese, less than about 0.15 wt. % iron, less than about 0.3 wt. % titanium and less than about 0.04 wt. % strontium, the balance aluminum with incidental elements and impurities, the alloy being substantially cooper-free, chromium-free and beryllium-free. 
     
     
       14. The aerospace component of  claim 13  wherein said composition contains about 6.5-8.0 wt. % silicon, about 0.45-0.7 wt. % magnesium, about 0.1-0.5 wt. % manganese, less than about 0.15 wt. % iron and less than about 0.2 wt. % titanium. 
     
     
       15. The aerospace component of  claim 13  which is high pressure die cast. 
     
     
       16. The aerospace component or  claim 13  which is squeeze east. 
     
     
       17. The aerospace component of  claim 13  which is semi solid formed. 
     
     
       18. The aerospace component of  claim 13  which has an ultimate tensile strength greater than about 45 ksi. 
     
     
       19. The aerospace component of  claim 18  which has an ultimate tensile strength greater than about 50 ksi. 
     
     
       20. The aerospace component of  claim 13  which is substantially blister-free.